In defence of CVTs: they’re actually not too bad these days

CVTs don't have any gears, but like the one in the 2015 Subaru WRX, their spreading popularity is probably a good thing

by
Brendan McAleer | June 17, 2014

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Ever try to heel and toe in a pair of wooden shoes? Me either, but I’ll bet it’s no picnic. And yet, more and more manufacturers would have you shift gears in a manner first popularized by the Dutch motor industry: the Continuously Variable Transmission.

Hoo boy, that phrase cleared the gearheads out in a hurry. One of Harry Potter’s wand-flinging semi-Latinate exhortations doesn’t have the magical auto-enthusiast-repulsion of a good Continuous Variableus! Mostly, people who like to drive don’t like to drive ’em.

But wait, here’s Subaru offering a CVT in their entirely new WRX, a car that many are praising as one of the best rally-rocket Subie to come along in years. Has the world gone mad?

Not at all. In fact, the CVT’s spreading popularity as the automatic transmission of choice is actually probably a good thing. Your fuel economy goes up. You can keep the engine singing in its powerband. A CVT might not have any gears, but that doesn’t mean it’s bad for gearheads.

To find the first mention of a variable ratio transmission, we have to look way back, and possibly learn to read mirror-written Italian. While you won’t find a sketch of a scrappy four-banger in Leonardo da Vinci’s notebook, you will find the plans for a stepless transmission with a theoretically infinite range of ratios. It’s hardly new technology – Leo jotted down the idea in 1490.

CVTs made their first automotive appearance in Dutch-made DAFs.

Early uses included power-operated milling and sawing, and the device was used in cars and motorcycles as early as the late 1800s. While the CVT was first popularized in low-powered scooters and the like, its first widely accepted automotive appearance was in the Dutch-built DAF 600. DAF called their version the Variomatic, and it would give the tiny, 590cc-engined family car some very odd characteristics.

First though, a look at what a Continuously Variable gearbox actually is, because they aren’t all the same. For instance, the Prius can claim to have an infinite number of gears between its highest and lowest ratios, but that’s a result of its planetary drive taking in a number of power outputs (from both electric and gasoline sources), and shunting the power around as needed.

More commonly, when we’re talking about a CVT-equipped passenger car with a conventional engine, the transmission in question is a belt-drive. Imagine, if you will, an 18-speed bicycle where the front and rear sprockets have been replaced by a pair of fattish cones. Instead of the stepped 18-speeds, you suddenly have gears like fifteen-and-a-half, or twelve-and-three-quarters.

Inside a CVT transmission, that’s essentially what’s happening. Instead of cones, you get a pair of v-sectioned pulleys that can each squeeze or expand to change their diameter. Because the belt must always stay the same length, as one shrinks, the other grows, in an infinite number of variations between top gear and lowest gear.

In the little DAF, that drive was an actual rubber belt, and it wasn’t exactly the most reliable thing in the world. They would break, and there are stories of ladies having to temporarily use their stockings to attempt a quick fix.

Subaru’s second crack at CVTs was with the “Lineartronic” transmission, introduced in 2010 with the Legacy and Outback

That wasn’t the only weird thing about the daffy DAF. Because reverse involved simply running the transmission backward, it had the same top-speed in both directions. At the now-defunct annual Dutch backward driving world championships (yes, really), the DAF proved itself unbeatable. There was also a control on the dash that would allow increased vacuum to cause the CVT to old lower gears and enhance engine braking – you could literally turn up how much it sucked.
Because each of the DAF’s rear wheels was propelled by its own drivebelt CVT, you had a sort of weird limited-slip arrangement. Handling in icy conditions was euphemistically described as “interesting,” even though power from the 590cc flat-twin engine was very modest.

Later, DAF would be snapped up by Volvo, which would eventually coincide with the CVT’s appearance in a motorsport that dovetails nicely with our so-equipped WRX: rallycross.

For some reason, Volvo decided their DAF-engineered 343 (a rear-drive hatchback we never got here) needed a bit more rough-and-tumble to its image. They therefore entered it in the European rallycross championships in the late 1970s, equipped with a 1.6L turbocharged engine and a DAF-designed CVT. Surprisingly, it did pretty well.

That wasn’t the only foray for the CVT into motorsport. Having a continuously variable gearset at the ready means that it’s possible to hold the powertrain right at its peak output level, a concept which attracted interest at the highest level. The Williams Formula One team experimented with a CVT transmission in the early 1990s, and while there were teething troubles with heat management, the potential was there. Sensing that only the best funded teams would be able to solve the associated transmission cooling issues, the FIA immediately banned the CVT as a forbidden performance enhancer. They also put the kaibosh on Audi’s early attempts to use a CVT in WRC-level rally racing.

For most Canadians, our earliest experiences with a CVT transmission came aboard a snowmobile. Makes perfect sense, then, that the first CVT-equipped car to reach Canadian shores in any numbers was the humble little Subaru Justy. Emphasis on humble.

Subaru then revised its CVT in 2012.

The odds of stumbling across a Justy today are pretty darn slim, as it wasn’t very popular compared to steadfast late-’80s econoboxes like the Nissan Micra. Part of the issue was a production bottleneck at the Van Doorne manufacturing plant – descendant of DAF – which could only produce so many metallic link belts for the transmission. The other part of the problem was that it wasn’t a very pleasant car to drive, performing like an office chair with a chihuahua attached to it with a bungee cord. Happily, things got better.

Benefits to a CVT include the ability to maximize acceleration by holding an engine at peak output. Under light acceleration, they can also keep revs down and thus maximize fuel economy by constantly shifting gears rather than raising rpms.

Drawbacks? Well, reliability has certainly been an issue. While early efforts relied on rubberized belt-drives that often broke, most modern CVTs are made of woven metal chains, and are thus extremely strong. That’s not to say issues don’t crop up, and when they do a rebuild is far more complex than with an ordinary automatic transmission. Generally, replacement rather than repair is the directive.

However, as the CVT has become widespread, their dependability has improved immeasurably. Their ability to handle higher torque applications is becoming more widespread, and the fuel-savings benefits increase as efforts are made to decrease the friction losses inherent in a belt-drive system.

Moreover, manufacturers have come up with solutions to the principle issue facing the CVT: feel. Because of the way a CVT holds constant engine speed, often-times drivers complain of a droning or a slack, rubberband feel. One of the more common comments is that a poorly calibrated CVT can feel like applying the throttle on a motorboat.

Keep the 2015 Subaru WRX in ‘Sport Sharp’ mode and you can shift through eight preset ratios.

The solution seems to be simulating the feel of a ordinary stepped automatic transmission. With Subaru’s CVT WRX, activating the most aggressive throttle mapping allows access to eight gear ratios through the paddle-shifters – because the transmission need not swap gears, but merely jump to a preset ratio, it shifts with the rapidity of a dual-clutch automatic, if not quite the crispness.

Leave everything as it is, and the CVT functions like a sort of a slingshot, with the turbocharged engine spooling up and the car snapping off after it. All-wheel-drive versions of the Nissan Juke function in much the same way, and because there’s no shifting, boost pressure is maintained at a constant.

Cast an eye on something with much less power like the Mitsubishi Mirage, and you won’t find much in the way of driving engagement. However, the combination of a CVT and a gentle right foot can net some excellent fuel economy benefits. The slower your acceleration, the lower the revs. With greatly reduced friction losses, CVT transmissions regularly beat manual transmissions, even in stop-and-go traffic. While the Mirage won’t win any beauty contests inside or out, it does function well as a efficient little city car when equipped with a CVT.

Nissan embraced the CVT fairly early on, and now offers it across the range. First to get the transmission was their Murano crossover, and while early versions did suffer from some reliability issues, it was considerably smoother and more efficient than a Pathfinder equipped with the same V6 engine. With the Versa, Sentra, and Altima, continual improvements in shift programming have reduced the laggy, rubber-band feel of Nissan’s CVTs, and considerable effort has been made to reduce friction losses. Slippage, that old bugbear of the early rubber belt-drive transmissions, is essentially a thing of the past.

As for Subaru’s decision to go for a CVT in their WRX, well, no-one who loves driving a stick is going to be swayed over to the dark side. However, as this is the sort of transmission you expect to find in a snowmobile, it somehow seems fitting that the first compact performance car to get it is a Subaru.

With the WRX, the CVT keeps the engine in the meaty areas of its powerband, making it a marvel in the twisties.

With a quick-spooling 2.0-litre direct-injection boxer engine that provides 258 lb.-ft. of torque as low as 2,000 rpm, the CVT-equipped WRX drives like a fired slingshot. Always on the boil in Sport Sharp mode, the driveline makes the most of the power and on a twisting backroad is no barrier to enjoyment. Need further convincing? At the launch of the new vehicle, four-time World Rally Champion Tommi Makinen admitted he’d actually prefer if the current generation of STI had the WRX’s variable transmission in it.

Of course, if you have the constellation of Pleiades tattooed on your bicep, you probably want the stick shift instead. But don’t deride it without driving it: the CVT is here to stay, and with each successive generation it gets a little bit better. Too bad this relentless improvement on moving forward has taken away the ability to drive backwards at full speed.